Furnace.



I. W. FOLTZ.

FURNACE. I APPLlCATION HLED JAN. 29. 19H.

SIIEETSMSHEEI l.

I. W. FOLTZ.

FURNACE.

UNITED STATES ram ouster;

IRA W. FOLTZ, 0F GHIGAGO, IZIJINOIS.

Specification of Letters Patent.

Patented Note 18, 1919.

Application filed January 29, 1917. Serial He. 145,164.

This invention relates to air heating up pliances for furnaces and is an improvement on a similar appliance disclosed in applic'ants copend'mg application for patent on furnaces, Serial No. 82,4514, filed March 6,

The objects of the invention are to rovide improved means whereby the air w ich supports mondary combustion nay be supplied through the furnace with .the air which supports primary combustion, or may be supplied independently of the air which supports primarv combustion; and to pro-' vide improved means for cleaning the sec ondary air supply appliance.

An illustrative embodiment of the invention is shown in the accompanying drawin s, in which- D t Figure 1 is a side elevation wltn the masonry in section of a furnace provided with the present improvements, and taken on line 1--1 of Fig. 2.

Fig. 2 is a transverse vertical section taken on the line A-A of Fig. 1.

Fl 3 is a sectional plan view taken on the line EE of Fig. 1.

Fig. 4 is a detail, partly in section, taken on the line 4-4 of Fig. 1, showing one of the adjustable doors for controlling an air inlet of the air supply conduits.

It has been to some extent recognized in this art that better results may be obtained in the combustion of solid fuel such as coal if, instead of permitting the entire air supply to pass through the fuel body, a separate or secondary supply of heated air be provided for the gases arising from the fuel and then the mixture of gases and air conducted to a region of fire and iiume that will cause their complete ignition. If all the air supplied to the furnace is permitted to enter the same at the ash-pit in a comparativcly cold state, and then to pass through the solid fuel, it may support a lively initial combustion m the solid matter of the fuel while the gases which are distilled from the solid fuel may buss oil unburned because oi": lack of suiiicient heat to ignite them, that is, there may be air sufli- .to insure the i 'nition of the distillutes.

cient in quantity but oil too low temperatuie t is therefore dillicult, under such conditions, to obtain good results in the burning of fuel irrespective of the quantity of fuel consumed in a. given time.

Various appliances have been proposed to provide means in furnaces for heating air which is independently supplied to the firebox above the fuel body or to the combustion chamber. Such appliances frequently require considerable alteration to be made in standard forms of furnaces when installed therein. Also, when such appliances were made of a good heat conducting material such as iron, they would rapidly deteriorate if so located in the furnace as to be subject to the en'ects of high temperatures occurring therein.

In the present case, the air heating appli auces extend along the boiler in order that the latter'may have some cooling eilecton said appliances and prevent the burning of the same while said, appliances are still rope-rly located and 0 rate satisfactorily in conducting the r quired heat" to the air passing through the appliances The drawings show-i1 return draft tubulur type of furnace wherein the boiler 1 is suspended by yokes 2 depending from transverse I-beams 3 in turn supported on the vertical pillars l. The masonry 5 which surrouiuls the boiler and forms the combustion chamber 6, the iire-box 7 and ash-pit 8 is preferably formed to provide a plurality of alternately restricted and enlarged pasin the combustion chamber for the purpose of causing eddy currents to insure good mixture of the air and gases passing through the furnace, and also to retard the flow oi the some to allow suilicient time for" luv 13 formed as shown in Fig. 3, which nora molly provides a heated surface 14 against.

which the gases impinge after passing through the open 12. At the rear of the grate and somew ut forward of the bridge wall 9 is a transversely extending arch or baffle 15 which is supported by the side walls A transverse wall 11 q thereof are controlled by doors oi the furnace and a central pillar l6 bei formed to provide passages 1? therctluounl from the lire-b0 or grate region to the combustion chamber. The arch l5 also is provided with vertical p2 sages; 18 having inlets 19 at the uppe par oi the lll'0-l)01-l ,and outlets ".20 immediately the rear of the fuel body 21 on grate 10.

This arrangement of ballle or arch at the rear of the fire-box, together with the lirebox li ing, provides a more or less inclosecl space within which gases may collect which arise from the fuel body 21.. These gases are conducted from said space through the Vertical channels 18 to the lame which normally sweeps by the outlets 2() of said passages from the burning fuel into the combustion chamber. p

The improvelil means for supplying heated air to the fire-box above the fuel. body courprises conduits 22 having inlets '23 in the ash-pit and from there leading upwardly through the side Walls 24 to horizontal con duits 25 located in m'onimit co the boiler and extending; from the i ll to the-rear end of the furnace. The conduits 25 lso extend through the front Wall 26 Where they are provided with additional air inlets 5472'. The air inlets 27 are controlled. by hinged doors 28. At the rear end oi? the furnace, conduits are connected with similarly 'forn'ied return conduits by an elbow l; to

The conduits :29 also pass through the front- Wall 26 oi the furnace, and the open ends 31. The conduits 29 communicate with. branch conduits 32 which provide outlets in the up per part of the fire-box above each 01' the firing doors 34-.

By the present arrangement of air heat-- ing conduits, the some may be installed. in furnaces of the general type shown Without much alteration thereof, and. While properly located to insure a sufficient supply of heated air for supportin secondary combustion, are not subject to t e excessive temperatures which occur in some parts of the furnace. In operation, the air supplied to the furnace will in the usual manner enter the same through the ash-pit door, a considerable quantity thereof sweeping upwardly and rearwardly through the fuel body and through the passages 17 into the combustion chamber. A quantity of a: liowerer, passes into the conduits 22, being drawn therethrougz'h by the natural draftof the furnace, which has a tendency to draw air from the outle through the upper part of the fire-box and through the open pas sages 18 leading into the combustion cham her. The flow of air through the air heating up liancc is considerably augmented by the e ect of the heat on the air therein. The heated air which delivered through the outlets 32 together with the gases arising from the :luel body,- may be further heated when traveling through the passages in arch l5, ignition taking place near the outlets LO of such passages when the mixture alrikcs the flame "which is emitted from the solid fuel and sweeps roarwardb through the :omhustiou chamber.

ll1e operation oi the furnace may be considcrably altered from that above described, for instance, the ash-pit door may be more or less closed and the secondary air supply taken through the inlets 27 of conduits 25. Thus the relative quantities of air for the primary and secondary combustion may be proportioned as desired by adjusting the doors 2'? and the ash pit door. For instance, a certain quantity of air may be entering the furnace through the ash-pit dqor, some of it passing through the grate and the solid fuel, while some of it enters the "eriical conduits 22, While the additional supply of air for the air heating appliance may be entering the same through the inlet 27, according" to the adjustment of door 28. In the normal operation of the furnace, the doors 28 and 31 may be closed. These doors necessary.

Although but one specific embodiment of this invention has been herein shown andv deecribed it will be understood that numerone details oi the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following cl aims.

I claim z- 1. A. furnace, comprising surrounding Walls forming an ash-pit, a fire boX and a combustion. chamber at the rear thereof, a boiler extending along the upper part of said firebox and combustion chamber, an air heating conduit leading upwardly from the ash-pit to the upper part of said firebox and. from there :Xtending rearwardly along said boiler into the combustion chamber and returning from the combustion chamber into the fire-box, said conduit hav ing an inlet and an outlet respectively in the uni-pit and fire-box, said conduit also having a branch extending through the wall of the furnace to the exterior thereof, and means for regulating the flow of air through said branch. I

2. A. furnace, comprising surrounding Walls forming an ash-pit, a firebox and a through the wall of the furnace to the exterior thereof, and menus for regulating the flow of air through said branch.

A furnace, comprising surrounding Walls forming an ash-pit, a fire-box and a combustion chamber at the rear thereof, an air heating conduit leading upwardly from the ash-pit to the upper part of said fire-box and from there extending rearwurdly into the combustion chamber and returning from the combustion chamber into the fire-box,

said conduit having an inlet and anoutlet respectively in the ash-pit and fire-box, said conduit also having a brunch extending through the wall of the furnace to theextprior thereof, in both the ingoing and outgoing portions thereof and means for regulating the flow of air through said branches.

Signed at Chicago this 25th day of January, 1917.

' IRA- W. FOLTZ. 

